So why do the CG Textures-based textures seem GPL-incompatible? Well, Marcel, CG Textures' administrator, wrote at least twice, that the textures on his website cannot be re-licensed under a free content license. Also the CG Textures license clearly states, that re-distribution of the textures and of derivate versions in texture form is prohibited.
The right to re-distribute is one of the pillars, on which free software, open source and free works stand. But it is not simple dogmatism which makes me agree with these definitions. When I create a piece of media for use in games, then I want to give others the ability to change it as easily as possible, so it fits their need. Because of this, it is vital that I am allowed to provide the source (the most raw/least edited form of the media) to them. This is not possible in the case of CG Textures. :(
However, TRaK has a permission to release his resulting textures under the GPL if he follows some conditions in creating these textures (which he did). These conditions only apply to TRaK, so the resulting textures are indeed free. Still his work is not to be included in OpenArena. I don't understand why.
A new community member named titi recently asked for a free texture reference image host and some of us recommended the public domain image gallery BurningWell.Org to him. He started uploading lots of files to it and even got permission to re-structure the gallery to optimize it for textures!
Hagish decided to set up a torrent tracker and to create a torrent of BurningWells' textures for easier downloading and for backup.
Although gallery, the system used by BurningWell.Org, might not be optimal for textures and although torrents are not perfect for sharing data that gets new additions frequently: there seems to be a bright future for free as in fancy pants freedom textures. :)